Usefulness of Ultrasound View of Larynx in Pre-Anesthetic Airway Assessment: A Comparison With Cormack-Lehane Classification During Direct Laryngoscopy Publisher



Mohammadi SS¹ ; Saliminia A¹ ; Nejatifard N¹ ; Azma R² Show Affiliations
Source: Anesthesiology and Pain Medicine Published:2016

Abstract

Background: One of the main challenges in anesthesiology is difficult intubation. There are many anatomical parameters for evaluating the feasibility of tracheal intubation; one that can reliably predict a difficult intubation is the Cormack-Lehane classification obtained during direct laryngoscopy. This is an invasive procedure that cannot be performed in an awake patient or for preanesthetic airway assessments in patients with no prior history of tracheal intubation. Recently, ultrasound has been successfully used for several airway-related applications. Objectives: The aim of this study was to compare and correlate the ultrasound view of the larynx with the Mallampati classification before anesthesia and the Cormack-Lehane classification during direct laryngoscopy under general anesthesia. Methods: This cross-sectional descriptive-analytic study included 53 ASA class I - III patients aged 18 - 70 years who were scheduled for tracheal intubation under general anesthesia. Before anesthesia, an oblique transverse ultrasound view of the airway was obtained; in addition, the total time taken to achieve the final plane, the depth of the pre-epiglottic space, and the distance from the epiglottis to the mid-point between the vocal cords were all recorded. The ultrasound measurements were then compared with the Mallampati class on the preoperative evaluation and with the Cormack-Lehane grade during direct laryngoscopy under general anesthesia. Results: It was observed that correlations between the pre-epiglottic space (PE) and Cormack-Lehane grades I, II, and III were weak. Correlations between the distance from the epiglottis to the vocal cords (E-VC) and Cormack-Lehane grades I, II, and III were also weak. The PE/E-VC ratio for correlations between the sonographic view and laryngoscopy had 87.5% sensitivity and 30% specificity. There was no correlation between Mallampati class and the PE/E-VC ratio (P = 0.566). Conclusions: Our study revealed weak correlation between PE/E-VC and Cormack-Lehane grade, with 87% sensitivity and 30% specificity. Therefore, we concluded that sonographic measurement criteria are not accurate in airway evaluations before anesthesia. © 2016, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM).